Pillow: Quadratic GIF comment copying during save

{
  "id": "4dde1252968d4f105b8301410a8d59c0f4d76f661a9a90bb0c0c1b1ba061a466",
  "url": "https://osv.dev/vulnerability/GHSA-fc9g-5qg7-mf45",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Pillow: Quadratic GIF comment copying during save",
    "summary": "On Pillow 12.3.0 and upstream `main` (`ad277e2761b489681e71b51e91367d46b0ceabb9`), a GIF with a long comment makes `_get_global_header()` copy portions of the comment repeatedly when saving, including comments carried over from untrusted images. I suggest provisional **Moderate** severity for crafted-image CPU denial of service, with CVSS-B 6.9 assuming a network service automatically opens unauthenticated uploads and they are resaved as GIFs; impact depends on input-size, concurrency, and worker CPU limits.",
    "evidence": "osv:GHSA-fc9g-5qg7-mf45",
    "products": [
      {
        "name": {
          "value": "pillow",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "13.0.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "10.0.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "10.0.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "10.1.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "10.2.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "10.3.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "10.4.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "11.0.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "11.1.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "11.2.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "11.3.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "12.0.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "12.1.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "12.1.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "12.2.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "12.3.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "9.2.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "9.3.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "9.4.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "9.5.0",
            "evidence": "/affected/0/versions"
          }
        ]
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "GHSA-fc9g-5qg7-mf45",
      "aliases": [
        "BIT-pillow-2026-112891",
        "CVE-2026-112891",
        "GHSA-fc9g-5qg7-mf45"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "9.2.0"
                },
                {
                  "fixed": "13.0.0"
                }
              ]
            }
          ],
          "package": {
            "name": "pillow",
            "purl": "pkg:pypi/pillow",
            "ecosystem": "PyPI"
          },
          "versions": [
            "10.0.0",
            "10.0.1",
            "10.1.0",
            "10.2.0",
            "10.3.0",
            "10.4.0",
            "11.0.0",
            "11.1.0",
            "11.2.1",
            "11.3.0",
            "12.0.0",
            "12.1.0",
            "12.1.1",
            "12.2.0",
            "12.3.0",
            "9.2.0",
            "9.3.0",
            "9.4.0",
            "9.5.0"
          ],
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-fc9g-5qg7-mf45/GHSA-fc9g-5qg7-mf45.json"
          }
        }
      ],
      "modified": "2026-10-26T08:56:06.483214483Z",
      "provider": "osv",
      "references": [
        "https://github.com/python-pillow/Pillow/security/advisories/GHSA-fc9g-5qg7-mf45",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-112891",
        "https://github.com/python-pillow/Pillow/commit/68a3fe957d8a4d552e8c69d96066d749f0614c7e",
        "https://github.com/python-pillow/Pillow",
        "https://github.com/python-pillow/Pillow/releases/tag/13.0.0"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-407"
        ],
        "severity": "MODERATE",
        "github_reviewed": true,
        "nvd_published_at": "2026-10-19T22:17:08Z",
        "github_reviewed_at": "2026-10-21T20:38:43Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-112891",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 446810,
  "published_at": "2026-10-21T20:38:43+00:00"
}